Turning an Old Joshua Tree Shed Into a Insulated Woodworking Shop

Mike Montgomery of Modern Builds is converting an old barn-style shed on his new Joshua Tree property into a woodworking workshop. The shed, he says, has decent bones but needs a lot of work, and the first job is a new concrete floor.

The slab

He and his friend Brett laid a grid of half-inch rebar on concrete riser blocks called dobies, which act like little feet and level everything. Expansion joint foam went around the perimeter so the slab can expand with heat. A truck delivered three yards, which he says cost about $300-$350.

The chute reached only about two-thirds of the way into the shed because of the door opening, so the driver, Dale, did a hot shot: throwing concrete from the chute with force to reach places it could not. They screeded with a straight 2×6 and finished with a rented bull float. The slab was not perfect; the front got rough because it began drying before they screeded toward the door.

To fix this he planned a flood coat. He ran spray foam around the 2×4 plate to make it waterproof, then mixed self-leveling underlayment thinner than pancake batter, three or four buckets at a time. He notes the mix is not as strong as typical concrete, and says it took the floor from a C minus to a B plus.

Structural fixes

One wall and a door were about to fall off the shed. They forced and clamped everything into place, screwed into secure header boards and added mending plates around the foundation. The old cabinets came out, and the 2×6 rafters turned out to be non-structural, held only by drywall screws to create a storage loft. After the plywood decking came out, the 2x6s followed, some with a sledgehammer. The center 4×6 beam is nailed in, so they lifted it a couple of feet and reused its brackets.

Loose exterior plywood got construction adhesive on every stud. Where it would not bend back, soaking it with water relieved the pressure and it nearly went back on its own, then screws held it. He added 2×4 blocks behind every exterior seam.

Light and roof

The high side of the single-slope roof is 10 feet and faces east. He removed the top two feet of the wall and fit 2 ft x 4 ft polycarbonate panels into the 24-inch opening using roofing screws with soft washers. Cuts used masking tape and a 60-tooth circular saw blade, and he left the plastic film on to mask the windows during painting.

The roof had a drip edge but no eave. As a quick repair he joined a 2×4 and 2×6 into a ledge and sealed the joint with waterproof seam tape, planning a corrugated panel roof later in the series.

Insulation and plywood

Spray foam sealed every seam, then R13 batts went into walls and ceiling, stapled by their paper flaps. Ceiling rafters are 18 inches apart and the panels 12 inches wide, so Brett ripped sheets and stitched pieces together. Plywood on the walls lets him screw wall-mounted organization anywhere. Half-inch plywood went on walls with 1/8 in. spacers for a reveal and a 3/4 in. riser at the floor; lighter 3/8 in. plywood went on the ceiling from scaffolding. He added 1×2 trim at corners and gaps and 1×4 trim beneath the polycarbonate, which also pulled bowed panels flat.